Catheter sheath introducers are well known in the health care industry as a means of providing access to the circulatory system for a number of applications. In a now well know process, the catheter sheath introducer is placed in a desired blood vessel to facilitate various procedures. Among these medical procedures is balloon angioplasty which requires the manipulation of long catheters through the circulatory system. Often much manipulation is needed to guide such catheters to the desired position in the body to effect the medical procedure. This manipulation causes strain to develop on the catheter introducer. Further, the mere lifting of the external parts of the introducer while it is in place causes strain between the sheath and the body of the introducer.
Catheter introducers have necessarily small parts with thin walls and small joining surfaces, as for example between the tubular sheath and hub, to allow for insertion into relatively small blood vessels. These small parts are susceptible to kinking and bending under the considerable strain produced when a catheter is introduced and subsequently moved. These movements may result from a medical procedure, the mere manipulation of the emplaced introducer, or simply by the patient rolling over.
Tubular sheaths have been manufactured with rigid plastics to overcome the problems of bending and kinking. Unfortunately, these materials may cause damage to the arterial walls. To avoid such damage to blood vessels, some introducer sheaths have been manufactured with flexible plastic-type materials, having high hoop strengths or with reinforcements, to help stop this kinking and bending while reducing tissue damage. For example, as described in Hillstead U.S. Pat. No. 5,066,285, the tubular sheath of a catheter sheath introducer is made of expanded, fibrous polytetrafluoroethylene (PTFE) so as to produce a more flexible sheath having a high hoop strength that resists kinking. Also, as described in Kocak U.S. Pat. Nos. 4,634,342 and 4,705,511, the tubular sheath of a catheter sheath introducer is made with a reinforcing helical spring molded into the sheath material so as to provide a flexible tube that is resistant to kinking.
These catheter sheaths are helpful in situations where the entry of the device into the anatomy causes the strain, such as when introducing the sheath through scar tissue. Specialized sheaths of this type are often more difficult to produce and costly to manufacture than regular sheaths. Further, the introduction of the sheath into the anatomy may not be the time at which the greatest strain is placed on all of the different segments of the catheter sheath introducer. Often after the catheter sheath introducer is emplaced the health-care provider will raise the hub of the introducer so as to insert a catheter. This raising of the hub places a large bending strain on the joining area of the hub and tubular sheath. The tubular sheath may bend or kink in this area as a result of this strain.
It is well known that the joining area of the tubular sheath and the hub is one of the weakest points in a catheter introducer structure. It is also known that this joining area is highly susceptible to strain. Although they are helpful in reducing bending and kinking, the above described sheath tubes may not help to reduce the strain placed at this area of the catheter sheath introducer. Further, although reinforced, a sheath tube such as the device disclosed in the Kocak patents may not have enough reinforcement to prevent the bending caused by the movement of the hub relative to the sheath tube. The results are that the introducers of the prior art are practical for insertion but problems can occur during the subsequent medical procedure.
I have invented a device that utilizes some of the same thin walled sheaths, to allow for comfortable insertion, as the prior introducers and provides a relief for the strain that causes kinking and bending at the joining area between the hub and sheath of the introducer.
It is therefore an object of the present invention to provide a catheter introducer of a size and proportion similar to currently and commercially available catheter introducers with strain relief to prevent kinking and bending of the sheath at the area where the introducer and the tubular sheath meet.
It is a further object of the present invention to provide a catheter sheath introducer with strain relieving means that is easy and economical to construct and use.
Other objects and advantages of the present invention will become apparent as the description proceeds.